1. Field of the Invention
The present invention relates generally to web printing presses and more particularly to a method and device for counterpoising a printing press cylinder.
2. Background Information
U.S. Pat. No. 5,429,048 to Gaffney et al. discloses an offset lithographic printing press in which a web of material to be printed passes through a series of print units. Each of the print units has an upper plate cylinder, an upper blanket cylinder, a lower blanket cylinder and a lower plate cylinder. Printing plates containing images may be fastened to the plate cylinders and gapless tubular-shaped blankets may be fastened to the blanket cylinders. During a printing operation, the web passes between the upper blanket and the lower blanket.
The tubular-shaped blanket of the printing press is attached and removed axially over the blanket cylinder. The blanket cylinder during operation is attached at both ends. However, for axial removal of the blanket, a door on the work side of the printing press is opened. As a result, the blanket cylinder is cantilevered and supported solely on the gear side of the press. To support the blanket cylinder during cantilevering, a counterpoise mechanism is located at the work side of the printing press.
U.S. Pat. No. 5,678,485 discloses a counterpoise and lift mechanism for use with a printing press having axially removable sleeves. Each cylinder to be cantilevered has a counterpoise mechanism having an actuating device, such as a pneumatic cylinder, and a counterpoise lever having an arc-shaped portion for interacting with a cylinder journal at the gear side end of the cylinder. The counterpoise mechanism moves between a disengaged position when the arc-shaped portion does not contact the cylinder journal and an engaged position when the arc shaped portion contacts the cylinder in a non-printing mode to allow for sleeve removal.
The counterpoise mechanisms of U.S. Pat. No. 5,678,485 are complicated and require large amounts of space. Adjustments may be cumbersome due to the various linkages. The mechanisms also are not well suited for a vertical web arrangement.
An object of the present invention is to provide a simple and reliable device to counterpoise a cylinder of a printing press. Another additional or alternative object is to provide a simple and reliable method for counterpoising a cylinder to be cantilevered on a printing press.
The present invention provides a counterpoise device including a first actuating device, a first counterpoise arm connected to the first actuating device for interacting with a cantilevered cylinder, a second actuating device, and a second counterpoise arm connected to the second actuating device for interacting with an other cantilevered cylinder. The first and the second counterpoise arms have a common pivot axis.
The counterpoise device of the present invention permits a compact and reliable support for the cylinders of the printing press, and also is particularly advantageous for vertical web designs, where a web of paper is running vertically.
The counterpoise device advantageously further includes an axle which provides the common pivot axis, the first and second counterpoise arms being pivotable about the axle. The counterpoise arms may include adjustable ends, so that the interaction with the cylinders can be adjusted easily. The adjustable ends also may be cam-driven to provide horizontal adjustment of the cylinder as well. The adjustable ends may be flat, or may be arc-shaped to fit tightly with a disk-shaped end of the cylinder.
Advantageously, the counterpoise arms are located directly above the cylinders, with bottom ends of the arms interacting with the cylinders and the top part of the arms connected to the actuating devices. Moreover, the two counterpoise arms preferably have meshing side surfaces facing each other, which touch each other when both counterpoise arms are deactivated.
The present invention also provides an offset vertical web press including a first blanket cylinder having a first end and a second end, and a first blanket disposed on the first blanket cylinder and axially removable over the second end. A second blanket cylinder is located aside the first blanket cylinder and has a third end and a fourth end. A second blanket is disposed on the second blanket cylinder and axially removable over the fourth end, the second blanket forming a nip with the first blanket for receiving a vertical web. A first counterpoise arm selectively supports the first end and a second counterpoise arm is connected, for example through an axle, to the first counterpoise arm for selectively supporting the third end.
The offset vertical web press of the present invention advantageously provides a compact design with axially removable blankets on counterpoised blanket cylinders. Advantageously, the first and second counterpoise arms may have a common pivot axis, which may be an axle.
The present invention also provides a method for removing gapless printing sleeves including rotating a first counterpoise arm about an axis so as to counterpoise a first end of a first cylinder, sliding a first print sleeve off of the first cylinder, rotating a second counterpoise arm about the axis so as to counterpoise a second end of a second cylinder, and sliding a second print sleeve off the second cylinder.
The use of the common axis provides a reliable and compact method for providing counterpoising to two cylinders.
Preferably, the print sleeves are blankets of an offset printing press. These blankets may be side-by-side blankets on an offset lithographic vertical web press. However, the print sleeves also may be sleeve-shaped plate cylinders, for example.
The first counterpoise arm and the second counterpoise arms preferably are rotated in different directions to effect the counterpoising, for example, the first arm being rotated counterclockwise and the second arm clockwise.